This invention relates generally to double post lifting mechanisms employing fluid operating cylinders and more specifically to hydraulic fluid driven double post automotive lifts. In addition to the structure of the double post lift assembly of the present invention, additional features include a safety latch mechanism for maintaining the article supporting carriage arms of the lift assembly at a position of maximum elevation even in the event of loss of hydraulic driving fluid pressure in the lifting cylinders and adjustable article supporting pads connected to the carriage arms which are tiltable through a vertical arc between stop members as the arms are raised and lowered.
Double post automotive lifts employing cylinders operated by hydraulic fluid supplied from a pressurized fluid source, generally speaking, have long been known in the prior art. See, for example, the automotive lift and safety latch mechanism disclosed in U.S. Pat. No. 4,241,901 issued to Donald F. Shircliffe on Dec. 30, 1980 and assigned to VBM Corporation, 1402 West Main Street, Louisville, Ky. A principal problem that has long existed in these double post lifting assemblies is the difficulty encountered in synchronizing the movement of the lifting posts so that the movable article supporting carriage assemblies track with one another in a synchronized manner throughout each lifting and lowering cycle. This problem was addressed in the Shircliffe patent wherein a complex mechanical assembly operated by the tension existing in a cable strung between the lifting posts was employed to maintain the carriage arms of each post in essentially level disposition.
In the event that the carriage arms become unsynchronized, the mechanical assembly of the subject structure actuates a pair of safety latches to stop further movement and unleveling of the carriage arms.
Additionally, in recent years, there has become a need for wheel alignment not only of the front wheels of an automobile but the rear wheels thereof as well. Front end wheel alignment is often accomplished using a conventional wheel alignment pit wherein the front wheels of an automobile are driven upon a pair of front wheel supporting pads cantilevered over one end of the pit. Rear wheel alignment requires lifting the rear wheels of the automobile clear of a supporting surface. While ordinary jacks are available for this purpose, they are not effective for rear wheel alignment purposes. It would, therefore, be desirable to provide a double post hydraulically operated lift assembly for lifting the rear wheels of the automobile off a supporting surface for rear wheel alignment purposes while allowing the front wheels to remain on the supporting pads extending over the pit. In other words, it would be desirable to provide such an assembly for lifting cantilevered loads partially supported thereby. In this manner, the alignment equipment employed in the nearby pit may be used in the rear wheel alignment procedure.
My invention accomplishes this objective and substantially overcomes the aformentioned problems encountered in prior art double post lift assemblies.